Bug Fixes

• async component: memory leak after synchronous async loading (#9275) d21e931, closes #9275 #9229
• core: dedupe lifecycle hooks during options merge 0d2e9c4, closes #9199
• core: fix merged twice bug when passing extended constructor to mixins (#9199) 743edac, closes #9199 #9198
• ssr: support rendering comment (#9128) b06c784, closes #9128